Process of making pyroxylin compounds.



UNITED STATES PATENT OFFICE.

WILLIAM G. LINDSAY, OF NEWARK, NEW JERSEY, ASSIGNOR TO THE GELLULOID COMPANY A CORPORATION OF NEW JERSEY.

PROCESS OF MAKING PTYROXYLIN COMPOUNDS.

Specification of Letters Patent.

Patented Jan. 28, 1919.

No Drawing. Original application filed May 11, 1916, Serial No. 96,791. Divided and this application filed June 15, 1917. Serial No. 174,903.

plication is a division of my appllcation, Se

rial No. 96,791, filed May 11, 1916.

Heretofore, it has been the usual practice to manufacture thermo-plastic compounds, of which celluloid is the principal example, by combining camphor with pyroxylin according to means which are well known to the art. 7

.It has been proposed to combine pyroxylin with other substances, mainly for the purpose of producing a cheaper product, in some cases for the u'rpose of producing an odorless pro uct, and in other instances to overcome the inflammability of the nitrocellulose; but, so far as I am aware, none of the substances, other than camphor, has met with any wide or extended application.

The various substances so proposed have been found to be more or less defective because of deficiency in solubility with respect to the alcoholic or volatile liquid solvent or with respect to the pyroxylin. Again, some are objectionable because of odor, or color, or other detrimental chemical and physical properties.

According to the present state of the art, camphor is the principal substance used in combination with pyroxylin for the manufacture of this articular class of pyroxylin compounds, an in commercial ractice few, if any oils or non-volatile liquld substances are used in single combination with pyroxylin in plastic combinations. Attempts to combine such oils or liquid substances with the yroxylin have met with difficulty owing to t e peculiar nature of such substances and their deficiency in requisite solvent action.

Heretofore, so far as I am aware, in all attempts to comblne such 011s or non-volatile.liquid substances with the pyroxylin, it has been thought necessary to first free the pyroxylin from the water remaining after washing out the nitratin acid, before combining t e pyroxylin wit the oil or liquid substance. In some cases, the pyroxylin is dehydrated by the use of alcohol and the non-volatile liquid then added, and in other cases the pyroxylin is dehydrated by pressure, absorption, or evaporation, and the oil or liquid is added previously mixed with alcohol, or mixed with the dehydrated or dried pyroxylin with subsequent addition of alcoholic solvent. In other words, the non-volatile liquid solvent is always added after the pyroxylin has been dried or freed from water to permit the required solvent action.

These processes are open to objection because of the necessity of using large quantities of volatile liquid solvents in order to bring about homogeneous penetration and the requisite uniform and complete combination between the non-volatile liquid and the pyroxylin.

So far as I am aware, it has never been suggested heretofore that, in the manufacture of pyroxylin compounds, a liquid as herein specified could be successfully introduced without first dehydrating the pyroxylin. This has doubtless been due to the greatly augmented and the penetration cilitated. This augmented solvent action which takes place after the elimination of the water greatly extends the successful application of these oils and liquids in the manufacture of pyroxylin plastic compounds.

,natural expectation that the means em-' The processwhich I have discovered consists in grinding the wet pyroxylin with the non-volatile liquid substance and treating the resultant mixture to pressure and absorption. By this means the water is expelled and the non-volatile liquid substance is retained by the pyroxylin, and on subsequent treatment with bibulous pads the remainder of the water is eliminated, or the finely-ground mixture of wet pyroxylin and liquid constituent may water by drying either at ordinary temperature under normal atmospheric condition or in a closed receptacle at a suitable temperature by means of diminished pressure.

The special class of liquids to which I refer are those which are substantially insoluble in water and are either non-volatile or substantially so. One example in this class is benzyl benzoate, the use of which is described in my United States Patent No.

961,360, dated June 14, 1910. Another exdroxyl group,

practically,

ample is liquid tricresylphosphate. Other examples will be found among the various essential oils of low volatility or other liquids which are known to possess either solvent power on the pyroxylin, or an affinity for it, especially such an aflinity as permits the rousing of solvent power by the action of a substance containing an hyas by the addition of alcohol, or other menstruum used in this art. In this class of non-volatile liquids, I also include such substances as castor oil, which, as is well known, has an appreciable affinity for pyro lin, especially under the stimulating in uence of alcohol or equivalent menstrua.

I also include any liquid which might be formed by mixing two solid solvents or substances useful in combinations of pyroxylin as part of the solvent -mixture. For example, I can use a mixture of triphenylphosphate and camphor, which form a liquid when mixed together, the preferred proportion for such elfect being 35 parts of camphor and parts of triphenylphosphate.

I also include camphor or other solid solvent in combination wth a fluid of relatively high boiling point which is substantially insoluble in water; for example, a. combination of camphor and fusel oil, though I prefer the use of a liquid which is in all of its elements, substantially non-volatile, z. e., a liquid which remains to a large degree a part of the finished combination and resembles camphor in that it imparts plasticity under heat to the final or substantially dry material.

I also include within the term liquid such oleaginous substances as have the above-stated characteristics pertaining to benzyl benzoate, castor oil, etc.

be freed from Y may teams In carrying out my process, I thoroughly. mix, preferably by grinding action, the hydrous pyroxylin with one or more members of the special class of solvents mentioned. After this thorough mixing, I preferably form the pulp into cakes and remove the water by pressure between bibulous pads, sometimes taking out the excess by a preliminary squeeze or equivalent means. Contrary to what might be supposed, it will be found that the water is extracted by itself and the liquids remain in combination with the pyroxylin. They are not absorbed away or pressed out with the water. In fact, there are indications that the solvent has actually assisted in dispelling the water by a sort of displacement action.

The resultant dried cake has the appearance of a camphor pyroxylin combination and, when subjected to'the usual subsequent operations, such as the addition of alcohol or other liquid solvents, presents the same features; '5. 6., the amount of such alcohol or other active liquid can be varied at will and the cake combination will present a union, or good mixture, of the non-volatile liquid solvent with the pyroxylin, as in the case of camphor. 7

While I prefer the pad and pressuremethod of removing the water, this may be accomplished by simply exposing the wet cake to the air, or by spreading out the wet pulp and allowing the water to evaporate. In such cases the pyroxylin is retained in 'sufliciently thorough combination with the non-volatile liquid solvent, and to a large extent the same advantages of control and good mixture whichfollow the use of' pressure and pads are secured. The further treatment of the compound is in accordance with the usual steps for the production of celluloid in suitable form. The material be mixed with pigments in the usual way and either rolled or kneaded according to well-known methods, or; by using agreater quantity of volatile solvent flowed as film, or in fact treated in any suitable manner according to the nature of the ultimate product desired. In my use of the term thermo-plastic herein, I mean moldable, and hence include thin sheets or. other products not specially designed for molding, but nevertheless possessing plastic properties.

' The action of the solvents is within the control of the operator, who will be guided in his selection and proportions by the desired character of the product and the peculiar activity of the menstrua. ,Although the object of my invention is primarily to facilitate the combination of the pyroxylin with such liquid solvents as are required or desired to remain largely in the finished product, I believe it to be the fact that the solvent power of the menstrua is given a better 1,809,81fi a opportunity for attaining its specific effect compound which consists in mixing'h drous 10 by reason of theprocess and that the operapyroxylin with benzyl benzoate an then tor will have less diflicult'y in securing the removing the water therefrom. desired conversion or solution than when 2. The process of making a pyroxylin 5 employing the older methods. v compound which consists in mixing hydrous Having thus described my invention, pyroxylin with benzyl benzoate and then 15 ghat I claim and desire to secure by Letters expressing the water therefrom.

atent is 1. The process of making a: pyroxylin WILLIAM G. LI NDSAY. 

